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121.
Monitoring the enforcement of an EU-wide ban of nitrofuran antibiotics in the food production chain is a challenging task,
given the nature of nitrofuran compounds. The original and modified Fenton reactions are advanced oxidation processes that
can eliminate the toxicity of nitrofurans. 2-(5-Nitrofuryl)acrylic acid (I) was degraded as a model compound by the original Fenton reaction with ferrous sulphate, by Mohr’s salt at pH 3 and 7, and
finally by advanced Fenton process (AFP) (Fe0/H2O2/H2SO4). In addition, the growth inhibition of Escherichia coli, a G− bacterium, was tested both before and after AFP treatment. The results showed that a small degradation efficiency of this
treatment process led to the toxicity changes and that the toxicity of I after AFP treatment process decreased. It seems that the treatment of polluted water using the Fenton reaction and its modifications
would be a suitable method for degradation of nitrofuran derivatives in polluted water. 相似文献
122.
Lukáš Gašparovič Ivan Hrablay Zuzana Vojteková Ľudovít Jelemenský 《Chemical Papers》2011,65(2):139-146
Activated sewage sludge samples obtained from two different waste water treatment plants were investigated by thermogravimetric
analysis. Due to a very high content of water in the sludge samples, these had to be dried at 160°C in an electrical oven
in order to remove all adsorbed water. To ensure pyrolysis conditions, nitrogen atmosphere was applied. The pyrolysis decomposition
process was carried out in the temperature range from ambient temperature to 900°C at three different heating rates: 2 K min−1, 5 K min−1, 10 K min−1. TGA and DTG curves of the decomposition processes were obtained. Temperature of onset decomposition, final temperature of
decomposition, maximum decomposition rate, and decomposition temperature were determined by thermogravimetric analysis for
both sludge samples used. The main decomposition process takes place at temperatures in the range from 230°C to 500°C. Above
this temperature, there are only small changes in the mass loss which are often attributed to the decomposition of carbonates
present in the sewage sludge samples. To determine the apparent kinetic parameters such as the activation energy and the preexponential
factor, the so called Friedman isoconversional method was used. Because of the requirements of this method, initial and final
parts of the decomposition process, where crossings of the decomposition lines occurred, were cut off. Obtained dependencies
of the apparent activation energies and preexponential factors as a function of conversion were used backwards to calculate
the modeled decomposition process of sewage sludge and the experimental data were in good accordance with the data obtained
by simulation. 相似文献
123.
Slobodan M. Radošević Milan R. PantićMilica V. Pavkov-Hrvojević Darko V. Kapor 《Annals of Physics》2013
We present the perturbation theory for lattice magnon fields of the D-dimensional O(3) Heisenberg ferromagnet. The effective Hamiltonian for the lattice magnon fields is obtained starting from the effective Lagrangian, with two dominant contributions that describe magnon–magnon interactions identified as a usual gradient term for the unit vector field and a part originating in the Wess–Zumino–Witten term of the effective Lagrangian. Feynman diagrams for lattice scalar fields with derivative couplings are introduced, on the basis of which we investigate the influence of magnon–magnon interactions on magnon self-energy and ferromagnet free energy. We also comment appearance of spurious terms in low-temperature series for the free energy by examining magnon–magnon interactions and internal symmetry of the effective Hamiltonian (Lagrangian). 相似文献
124.
Hydrated pastes of ordinary Portland cement prepared with different water-to-cement ratios were investigated by using the small-angle neutron scattering technique in the region of Q ∈ (0.0045, 0.11) Å?1. Samples of cement pastes were subjected to non-standard hydration conditions using a mix with D2O, low RH, and water-to-cement ratios spread over a very wide interval (0.4; 1.4). The investigation was focused on testing the structural stability of nano-metric particles in the cement C-S-H gel. Owing to the high structural stability of these nano-particles, their average diameter might be used as a microscopic parameter characterizing the nano-metric structure of C-S-H gels. The average diameter of the nano-particles of the studied ordinary Portland cement CEMI 42.5 R-SC was found to be close to the value of 4.2 nm and independent of the water-to-cement ratios. 相似文献
125.
Nowadays the discussion on the symbiosis of the international and national nomenclature systems in different areas of science provides clear evidences that full implementation of conventional international (mainly English) nomenclature principles in the local ones is sometimes not only unnecessary, but even redundant or impossible. Rapid development of natural sciences necessitates creation of accurate, comprehensive and comprehensible nomenclature systems for objects and phenomena under research. This study outlines the origins and development of the Slovak chemical nomenclature which is based on the Czech model. We analyze the unique Slovak nomenclature items as well as the re-evaluation of linguistic means in the field of inorganic chemistry in the international context. A part of this work is devoted to the syntactical structure of the names of inorganic compounds. At the same time we draw a parallel between chemical nomenclature and the phenomenon of controlled language. 相似文献
126.
127.
Agneš Kapor Vesna Nikolić Ljubiša Nikolić Mihajlo Stanković Milorad Cakić Ljiljana Stanojević Dušica Ilić 《Central European Journal of Chemistry》2010,8(4):834-841
In this paper the procedure for the preparation of inclusion complexes of amlodipine besylate with β-cyclodextrin (β-CD) and
2-hydrohypropyl-β-cyclodextrin (HPβ-CD) and their structural characterization was described. Molecular inclusion complexes
of amlodipine besylate are prepared by the coprecipitation method and characterised by the application of spectroscopic methods
FTIR, 1H-NMR and XRD. The photosensitivity of amlodipine besylate in the inclusion complexes was also determined with respect to
uncomplexed agent. DSC curves indicate the loss of the clear peak due to melting of amlodipine besylate at about 200°C, while
on XR diffractograms certain reflections are lost belonging to amlodipine besylate in complexes. This indicates its inclusion
in the vacancies of the host. The inclusion of amlodipine besylate with cyclodextrins increases the stability, i.e. decreases the photosensitivity of amlodipine besylate.
相似文献
128.
Vesna Nikolić Dušica Ilić Ljubiša Nikolić Mihajlo Stanković Milorad Cakić Ljiljana Stanojević Agneš Kapor Mirjana Popsavin 《Central European Journal of Chemistry》2010,8(4):744-749
The inclusion complex β-cyclodextrin:nifedipin was prepared in solid state by coprecipitation with 1:1 mol ratio. The structure
of the obtained complex and nifedipin was characterized by use of X-ray diffraction (XR), infrared spectroscopy (FTIR), nuclear
magnetic resonance (NMR), and differential scanning calorimetry (DSC) methods. The photodegradation of nifedipin and the β-cyclodextrin:nifedipin
inclusion complex in solid state was monitored under natural daylight by infrared spectroscopy, whereby the free nifedipin
degraded four to five times faster than the complexed nifedipin. The photodegradation products of both free and complexed
nifedipin, formed during irradiation at 350 nm (with corresponding energy flux of 18 W m−2) were monitored by liquid chromatography during various time intervals. The speed of formation of nitroso- and nitro-phenyl
derivatives by nifedipin irradiation was significantly higher than those of complexed nifedipin irradiation, which indicates
its increased photostability in the inclusion complex. The effect on this property is significant because it contributes both
to the improvement of the therapeutic effect of nifedipin and to the safer application thereof.
相似文献
129.
Pyrolysis of a wood chips mixture and main wood compounds such as hemicellulose, cellulose and lignin was investigated by
thermogravimetry. The investigation was carried out in inert nitrogen atmosphere with temperatures ranging from 20°C to 900°C
for four heating rates: 2 K min−1, 5 K min−1, 10 K min−1, and 15 K min−1. Hemicellulose, cellulose, and lignin were used as the main compounds of biomass. TGA and DTG temperature dependencies were
evaluated. Decomposition processes proceed in three main stages: water evaporation, and active and passive pyrolysis. The
decomposition of hemicellulose and cellulose takes place in the temperature range of 200–380°C and 250–380°C, while lignin
decomposition seems to be ranging from 180°C up to 900°C. The isoconversional method was used to determine kinetic parameters
such as activation energy and pre-exponential factor mainly in the stage of active pyrolysis and partially in the passive
stage. It was found that, at the end of the decomposition process, the value of activation energy decreases. Reaction order
does not have a significant influence on the process because of the high value of the pre-exponential factor. Obtained kinetic
parameters were used to calculate simulated decompositions at different heating rates. Experimental data compared with the
simulation ones were in good accordance at all heating rates. From the pyrolysis of hemicellulose, cellulose, and lignin it
is clear that the decomposition process of wood is dependent on the composition and concentration of the main compounds. 相似文献
130.
Branko Grünbaum Tomáš Kaiser Daniel Král’ Moshe Rosenfeld 《Israel Journal of Mathematics》2010,179(1):235-252
A polytope P with 2n vertices is called equipartite if for any partition of its vertex set into two equal-size sets V
1 and V
2, there is an isometry of the polytope P that maps V
1 onto V
2. We prove that an equipartite polytope in ℝ
d
can have at most 2d+2 vertices. We show that this bound is sharp and identify all known equipartite polytopes in ℝ
d
. We conjecture that the list is complete. 相似文献